// 新建 karma.conf.js，内容如下
module.exports = function (config) {
  config.set({

      // base path that will be used to resolve all patterns (eg. files, exclude)
      basePath: '',
         // frameworks to use
         // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
         frameworks: ['mocha', 'sinon-chai'],
         client: {
             chai: {
                 includeStack: true
             }
         },


         // list of files / patterns to load in the browser
         files: [
             'dist/**/*.test.js',
             'dist/**/*.test.css'
         ],


         // list of files / patterns to exclude
         exclude: [],


         // preprocess matching files before serving them to the browser
         // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
         preprocessors: {},


         // test results reporter to use
         // possible values: 'dots', 'progress'
         // available reporters: https://npmjs.org/browse/keyword/karma-reporter
         reporters: ['progress'],


         // web server port
         port: 9876,


         // enable / disable colors in the output (reporters and logs)
         colors: true,


         // level of logging
         // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
         logLevel: config.LOG_INFO,


         // enable / disable watching file and executing tests whenever any file changes
         autoWatch: true,


         // start these browsers
         // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
         browsers: ['ChromeHeadless'],


         // Continuous Integration mode
         // if true, Karma captures browsers, runs the tests and exits
         singleRun: false,

         // Concurrency level
         // how many browser should be started simultaneous
         concurrency: Infinity
     })
 }